Image processing apparatus and method

Abstract

An image processing apparatus and a method for processing an image. The image processing apparatus includes circuitry configured to set a current quantization parameter for a current coding block in a layer lower than a layer of a largest coding block and a quantization parameter based on a difference between the current quantization parameter for the current coding block and a slice quantization parameter for a slice in which the current coding block is located. The circuitry quantizes image data to generate quantized data based on the current quantization parameter. Further, the circuitry codes the generated quantized data in a coding block including a hierarchical structure to generate a code data including the quantization parameter.

The invention claimed is: 
     
       1. An image processing apparatus, comprising:
 circuitry configured to
 set a current quantization parameter for a current coding block formed by block partitioning, which recursively splits a current largest coding block into smaller coding blocks, and a quantization parameter based on a difference between the current quantization parameter for the current coding block and a slice quantization parameter for a slice containing the current largest coding block and the current coding block, 
 quantize transform coefficient data using the current quantization parameter for the current coding block to generate quantized data, and 
 code the quantized data to generate a bit stream including the quantization parameter. 
 
 
     
     
       2. The image processing apparatus according to  claim 1 , wherein
 the circuitry is configured to set the current quantization parameter for the current coding block based on a value indicating a minimum coding block size for which a difference quantization parameter is set. 
 
     
     
       3. The image processing apparatus according to  claim 2 , wherein
 the difference quantization parameter is based on a difference between the current quantization parameter for the current coding block and a previous quantization parameter for a previous coding block. 
 
     
     
       4. The image processing apparatus according to  claim 3 , wherein
 the previous coding block is a coding block that is decoded immediately before the current coding block in the order the coded data is to be decoded. 
 
     
     
       5. A method of an image processing apparatus for processing an image, the method comprising:
 setting, by circuitry of the image processing apparatus, a current quantization parameter for a current coding block formed by block partitioning, which recursively splits a current largest coding block into smaller coding blocks, and a quantization parameter based on a difference between the current quantization parameter for the current coding block and a slice quantization parameter for a slice containing the current largest coding block and the current coding block; 
 quantizing, by the circuitry, transform coefficient data using the current quantization parameter for the current coding block to generate quantized data; and 
 coding the quantized data to generate a bit stream including the quantization parameter. 
 
     
     
       6. The method according to  claim 5 , wherein the step of setting the quantization parameter comprises:
 setting the current quantization parameter for the current coding block based on a value indicating a minimum coding block size for which a difference quantization parameter is set. 
 
     
     
       7. The method according to  claim 6 , wherein
 the difference quantization parameter is based on a difference between the current quantization parameter for the current coding block and a previous quantization parameter for a previous coding block. 
 
     
     
       8. The image processing apparatus according to  claim 7 , wherein
 the previous coding block is a coding block that is decoded immediately before the current coding block in the order the coded data is to be decoded.